Pasture drop with dry spell

Rainfall across Wairarapa has reached about half the usual December totals with a week to go, as DairyNZ predicts a drop in pasture and milk production into the new year.

As at Christmas Eve on Thursday, rainfall figures for Greater Wellington were lowest at Waiorongomai in South Wairarapa, with a total of 44.5mm - when the total for the full month is usually 117mm.

East in the Tinui Valley the rain gauge read 49mm, tracking well below the average monthly total of 93mm.

In the Tararua Ranges, 268.5mm had fallen by Thursday, less than half the average for the month, which is 599mm.

At Tauherenikau the full month total is usually 80mm, but just 55.4mm had fallen with a week to go.

DairyNZ has gathered data from previous dry years that suggests that many dairy farms could grow 2-3 tonnes less feed per hectare than normal.

DairyNZ senior developer for productivity Kim Mashlan said many areas "show lower than average pasture growth rates from January through to April, compared to an average year".

Ms Mashlan said the information "highlights the importance of preparing for the worst and hoping for the best, which many farmers are already doing".

The data comes from the three strongest El Nino years, which the forecast for this summer is expected to mirror.

Those years are 1972-73, 1982-83 and 1997-98.

DairyNZ economist Matthew Newman said milk production nationwide was already well below last year, after farmers culled cow numbers heavily earlier in the season because of a low milk price.

Mr Newman said if dry summer conditions put pressure on pasture growth, then milk production would drop further.

"Currently, I'd say we are tracking for a 6 per cent drop in milk production this season. But if El Nino conditions affect us badly ... it could be 10 per cent or more down in some regions."